A Perspective on the Milky Way Bulge Bar as Seen from the Neutron-capture Elements Cerium and Neodymium with APOGEE

Journal Article · Mon Apr 01 00:00:00 EDT 2024 · The Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/ad28c2· OSTI ID:2583047

Sales-Silva, J.; Cunha, K.; Smith, V.; Daflon, S.; Souto, D.; Guerço, R.; Queiroz, A.; Chiappini, C.; Hayes, C.; Masseron, T.; Hasselquist, Sten; Horta, D.; Prantzos, N.; Zoccali, M.; Allende Prieto, C.; Barbuy, B.; Beaton, R.; Bizyaev, D.; Fernández-Trincado, J.; Frinchaboy, P. ; Holtzman, J.; Johnson, J.; Jönsson, Henrik; Majewski, S.; Minniti, D.; Nidever, D.; Schiavon, R.; Schultheis, M.; Sobeck, J.; Stringfellow, G.; Zasowski, G.

Abstract

This study probes the chemical abundances of the neutron-capture elements cerium and neodymium in the inner Milky Way from an analysis of a sample of ∼2000 stars in the Galactic bulge bar spatially contained within ∣X_Gal∣ < 5 kpc, ∣Y_Gal∣ < 3.5 kpc, and ∣Z_Gal∣ < 1 kpc, and spanning metallicities between −2.0 ≲ [Fe/H] ≲ +0.5. We classify the sample stars into low- or high-[Mg/Fe] populations and find that, in general, values of [Ce/Fe] and [Nd/Fe] increase as the metallicity decreases for the low- and high-[Mg/Fe] populations. Ce abundances show a more complex variation across the metallicity range of our bulge-bar sample when compared to Nd, with ther-process dominating the production of neutron-capture elements in the high-[Mg/Fe] population ([Ce/Nd] < 0.0). We find a spatial chemical dependence of Ce and Nd abundances for our sample of bulge-bar stars, with low- and high-[Mg/Fe] populations displaying a distinct abundance distribution. In the region close to the center of the MW, the low-[Mg/Fe] population is dominated by stars with low [Ce/Fe], [Ce/Mg], [Nd/Mg], [Nd/Fe], and [Ce/Nd] ratios. The low [Ce/Nd] ratio indicates a significant contribution in this central region fromr-process yields for the low-[Mg/Fe] population. The chemical pattern of the most metal-poor stars in our sample suggests an early chemical enrichment of the bulge dominated by yields from core-collapse supernovae andr-process astrophysical sites, such as magnetorotational supernovae.

• Research Organization: National Renewable Energy Laboratory (NREL), Golden, CO (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: AC36-08GO28308
• OSTI ID: 2583047
• Journal Information: The Astrophysical Journal, Journal Name: The Astrophysical Journal Journal Issue: 2 Vol. 965; ISSN 0004-637X
• Publisher: IOP Publishing
• Country of Publication: United States
• Language: English

Related Subjects

Astronomy &amp; Astrophysics